Treatment of hides, skins, and the like



. I No Drawing.

Patented may 18, 1926,

- UNITED STATES PATENT OFFICE.

CHARLES JOSEPH MICHEL MARIE LE PIEI'IJI'JJ, OF PARIS, FRANCE, ASSIGNOlR OF ONE- FIFTH TO JAMES STUART BURNS, OF LONDON, ENGLAND. Y

. TREATMENT OF HIDE-S, SKINS, AND THE LIKE.

The present invention is for improvements in and relating to the treatmentof hides, skins, and the like, hereinafter referred to as hides, and has particular reference to the provision of a preliminary dressing process preparatory to tanning. The invention concerns that class of process in which the hide is treated in a bath containing the type of.

ferments known as enzymes.

The invention is based upon the discovery that if hides, skins or the like he treated with an enzyme bath as hereinafter set forth, there is produced, instead of a depleting action such as is so characteristic of the use of tryptic and other animal ferments of like action, quite the reverse effect when the treated material is subsequently subjected to tanning. The leather is markedly thickened as well as being of high quality and texture, and the purpose of that feature of the present invention which consists in a process of treatment of the hide or skin preparatory to and in conjunction with tanning is to facilitate the tanning process and to obtain a finished product of the improved properties evidenced by increased thickness and weight and quality of leather, together with good tensile strength and wear, the combination of the preparatory and tanning processes swelling the hide producing added weight, thickness and durability. The invention is particularly applicable to the treatment of heavy hides. and it will be appreciated that the extent of improvement in respect of one or more of the properties mentioned is dependent upon the nature of the raw material, other conditions remaining, the same.

According to this invention, the aforesaid tanning preparatory process for the purpose described consists in treating the hide, skin or the like in an exclusively vegetable-derived lipolytic bath of acid reaction (preferably acid with an organic acid, such as butyric or lactic acid) in presence of an agent or agents promotive of the lipolytic action of the ferments, such as a lipase activator (for example, a manganese salt, such as manganese sulphate), or a fatemulsifying agent, (for example, an alkali sulphoricinate, such as sodium sulphoricinate). v

Thus, the hide may be treated with the Application filed December 11, 1923. Serial No. 680,041.

,a liquor (appropriately acidified as may be required, preferably with an organic acid such as butyricor lactic-acid) derived from the fermentation in presence of an activator such as manganese sulphate of castor-oil seeds or castor oil seed residues in water.

It is preferred to use castor-oil seeds as pure and fresh as are obtainable. The seeds may be oil-extracted, and both the pulp and the shells may be used for preparing. the bath, the use of the Whole seed being preferred.

It has been found that an exclusively vegetable lipolytic enzyme bath possesses the property of facilitating the tanning operation and improving the quality of the leather produced thereby, but it does not necessarily follow that the action of the bath in this respect is to be attributed solely to the lipolytic ferment, and other substances present in the material from which the lipolytic ferment is derived may play their part in the process. The expression vegetablederived lipolytic bath as used herein is three-quarters of a pound of bisulphite of sodium and one-quarter of a pound of butyric-acid .per hundred pounds of water, the temperature of the bath being not less than 12 C. 'The process may be considerablyexpedited by efiecting the treatment in a drum. The hide for treatment in the tan- I ning preparatory bath should be of neutral reaction or slightly acid, an organic acid being preferably employed as aforesaid.

The tanning preparatory process may be carried out at any desired temperature acquality product, may be generally obtained 11k when the liquor is maintained at approximately the same temperature as that of the live hide, that is, about 35 to 38 C.

The bath may advantageously contain a reagent, such as sodium fluoride, which possesses the property of inhibiting counter fermentations or putrefactive changes, and it will be frequently found advantageous to make a fresh addition of such reagent to the liquor prior to treatment therewith of a fresh batch of hides. lVhen the latter are in good condition, a comparatively small proportion of such a reagent, for example,

' one pound of sodium fluoride per ton of the liquor, will generally be found to be sufficientin order to maintain a normal fermentation. In the contrary case, or where at any stage in the process indications are shown of the commencement of putrefactive change, the proportion should be increased,

for example, to eight-and-a-half pounds of sodium fluoride per ton of the liquor, and increase in the quantity of such an inhibitive reagent is in any case a good precautionary measure as a general rule "in hot weather.

Over-exposure to the action of the bath may result in shrinkage or like undesired change of the material, to the defeat of the aforementioned purpose of the preparatory treatment, and the latter is therefore to be understood as conducted according to this invention only to such a stage as to achieve this purpose in contradistinction to depletion of the material. consequently, be kept under careful observation,being removed from time to time, as may be found necessary, for inspection. For some hides, with a well-fermented bath, onehalf hour may suffice, while in the case of others one and one-half hours or more may be required to give the desired aforementioned results, but as will be appreciated a rule applicable to all cases cannot be laid down, and the time may be varied according to the nature of the particular hide, and the Ic)ha}rl1ges observed during treatment in the at L It is of course known in fermentation reactions to add a reagent inimical to putrefactive change to the reaction mixture, and no claim is made herein to the general use of preservatives for this purpose.

The preferred preparatory bath is pr epared by the fermentation of castor-oil seeds appropriately disintegrated, in an aqueous medium, with or without caster-oil, in pres.-

Which is gradually increased.

The goods should.

ence. of a lipase-activator, such, for example, i

as a manganese salt.

A'fat-emulsifying agent may be added to the mixture (for example, an alkali sulphoricinate, such as sodium sulphoricinate) or said agent may be added to the bath before introduction therein of the hide or the The fermentation may be effected at a temperature substantially between 26 to 28 C.

F or reasonably expeditious preparation, the proportion of the liquid component of the fermentation mixture should not exceed about four times the weight of seed-pulp.

After conclusion of the fermentation which, at the temperature stated, may take from 48 to hours, the addition may be made to the liquor of a reagent such as sodium fluoride for the purpose previously mentioned.

The liquor so obtained, with or without dilution, as may be found convenient, may be directly applied as a tanning preparatory bath. It is, however, preferred to utilize a liquor which has been sown with a culture of lactic yeast, this addition appearing generally to improve the bath and the course of the reactions going forward therein. The latter may itself advantageously be activated liquor.

The activation of the yeast may be effecttaining initially a very small proportion of sulphoricinate of sodium, the proportion of A small quantity of castor-oil seed pulp may also be added to the culture sulphoricinate solution used for cultivating the yeast. A satisfactory degree of development is obtained by leaving the yeast culture to stand at a temperature of about 28 C. over a period of from two to three days. The temperature control of the fermentation should be care fully observed.

This east culture may be added to the liquor obtained by the fermentation of the castor-oil seeds, or may be added to*tl1e initial mixture prior to fermentation of the seeds. The latter procedure is to be preferred as then a Strong and active lactic fermen'tation takesplace in'the bath from the commencement, and although this fermentation has little or no influence on the lipaseidic reaction, it tends to prevent counter fermentations during the ripening of the bath. O

In any event, the addition to the prepared bath of sodium fluoride or other reagent of similar properties is to be recommended.

In preparing a bath in one way according of about'two days.

' centrifuged, the mud and seed residues being preserved for the preparation of a fresh mixture, and to the liquor was added fluoride of sodium in the proportion of one pound of the salt per ton of liquor.

The treatment of the hide may be efiected by working the hide in the liquor, for example with a drum or paddle tumbler, in the customary manner, as may be desired. Among the results of treatment in a medium of this type is the digestion of fatty matters and also of some of the protein constituents in the goods, and an opening of the pores of the material as well as an acceleration of the subsequent tanning process and, in general, an improvement in the quality of the material finally obtained. The treated hide possesses an improved absorptive power for tanning extracts, a high degree of absorption, with consequent increase in thickness and weight of the hide as already referred to, being effected by a materially shortened treatment, with the production of a wellcured and good wearing leather.

Acidification of the bath which, as previously mentioned, is preferably effected with an-organic acid, should be such as to maintain a slight acid reaction throughout the process of treatment of the hides and the like, and the acidity may be maintained'by addition of acid during the process as may be required. Where developing lactic yeast, or the fermentation product thereof is employed in the bath, it may not be necessary to make any further addition of organic acid in order to maintain an acid reaction.

Priorto treatment in the tanning rep-aratory bath the hide may be subjected to any desired preliminary dressing as is custom ary in the art. The hide may be dehaired by a desired process. Preferably, however, depilation is effected by aqueous sodium sulphide and caustic alkali, the goods being thereafter treated with a solution of bisulphite of sodium in'water, and then submitted to the action of a bath consisting essentially of an aqueous solution of an organic acid, such as formic, butyric, or acetic acid, to which may be added fluoride, with or without sodium chloride.

In effecting the tanning of the material which has been submitted to the foregoing preparatory treatment, it is preferred to'subject the goods to tanning liquors of regularly increasing specific gravity, say from about 0.5 to 12 Baum, while the temperature from beginning to end of the tanning operations, that is to say in the handlers and in the drums and bark-tanning pits, is maintained substantially at 36 C.

The increase in specific gravity of the liquors is preferably 0.5 at a time, and the period of treatment of the goods in successive liquors may be from one, two, three, or

four hours up to eight hours.

Prior to introduction into the tanning liquor, the prepared material should be washed, advantageously in a dilute alkali bath, e. g. one containing about two-and-ahalf pounds of caustic soda per ton of water, the material being subsequently washed free from alkali with water or dilute acid. Alternatively, or in conjunction with one or more of these washings, it is recommended, particularly when the hides are to be tanned with tanning extracts, to put into the tanning drums a mixture of soluble mineral oil (sulphonated mineral oil), sulphoricinate of I soda, and an essential oil, such as turpentine, in substantially the proportions of Kilos. Soluble mineral oil '80 Sulphoricinate of soda 10 Turpentine oil 3 per ton of hides under treatment. This addition should preferably be made during the first period (of nine. hours) of drumming and with a tannin extract of not more than 9 Baum.

The tanning liquors may also contain a certain proportion of chloride of sodium, and there may be added a liquid hydrocarbon, or chlorine derivative thereof, for example, petrol, carbon tetrachloride, acetylene tetrachloride, or bisulphide of carbon.

It has been found that by conducting the tanning process under these conditions, not only is the quality of the leather improved, but the rocess is accelerated and the cost of productlon reduced. For instance, no subsequent drumming is necessary, and products are obtainable in a few weeks which by the usual method of production demand several months or, in some cases, even years for their preparation.

I claim:

1. A tanning preparatory process for the purpose described which consists in submitting the hide to the action of exclusively vegetable-derived lipolytic ferments in an acid medium in presence of an agent promotive of the lipolytic action of the ferments.

2. A tanning preparatory process for the purpose described which consistsin submitting the hide to the action of exclusively ,vegetable-derived lipolytfc ferments in an acid medium in presence of sodium fluoride and of an agent promotive of the lipolytic tor.

ting thehide to the action of exclusively vegetable-derived lipolytic ferments in an acid medium in presence of a lipase activa- 4. tanning preparatory process for the purpose described which consists in submitting the hide to the action of exclusively vegetable-derived lipolytic ferments in an acid medium in presence of a lipase activator and a fat-emulsifying agent.

5. A tanning preparatory process for the purpose described which consists in submitting the hide tothe action of exclusively vegetable-derh'ed lipolytic ferments in an acid medium in presence of a lipase activator and an alkali sulphoricinate. 6. A tanning preparatory process for the purpose described which consists in submitting the hide to the action of exclusively vegetable-derived lipolytic ferments in an acid medium in presence of an agent promotiveof, the lipolytic action of the ferments and in presence of the fermentation products of lactic yeast.

7. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of a lipase activator of a vegetable lipase-yielding material in an aqueous medium.

8. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of a lipase activator of a vegetable lipase-yielding material an aqueous medium, and containing sodium fluoride.

9. A tanning preparatory process for the purpose described which conslsts in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of a lipase activator of a vegetable lipase-yielding material in an aqueous medium, and containing a fat-emulsifying agent.

10. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of a lipase activator of castor oil seeds in an aqueous medium.

11. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of manganese sulphate of castor oil seeds in an aqueous medium.

12. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the prior fermentation in presence of a lipase activator of castor oil seeds in an a ueous medium, and containing a fat-emuL sl tylng agent.

13. A tanning preparatory process for the masses purpose described which consists in treat ing the hide witha bath of acid reaction derived from the prior fermentation in presence of a lipase activator of castor oil seeds in an aqueous medium, and containing fermentation products of lactic yeast.

14. A tanning preparatory process for the purpose described which consists in treating the hide with a bath of acid reaction derived from the fermentation in presence of manganese sulphate of caster oil seeds in an aqueous medium, and containing an alkali sulphoricinate.

15. A tanning preparatory process for the purpose described which consists in treating the hide in a bath of acid reaction with an organic acid, derived from the prior fermentation in presence of a lipase activator of castor oil seeds in an aqueous medium. I

16. A tanning preparatory process for the purpose described which consists in submitting the hide to the action of exclusively vegetable-derived lipolytic ferments in an acid medium in presence of an agent promotive of the lipolytic action of the ferments at a temperature corresponding substantially to that of the live hide.

17. A process of mak' a tanning preparatory liquor which consists in fermenting a vegetable lipase-yielding material in an aqueous mediumin presence of a lipase activator.

18. A process ofmaking a tanning prepar atory liquor which consists in fermenting a mixture comprising water and disintegrated castor oil seed in presence of a lipase activator.

19. A process of making a tanning preparatory liquor which consists in fermenting a mixture comprising water and disintegrated castor oil seed in presence of manganese sulphate.

20. A process for making a tanning preparatory liquor which consists in fermenting in presence of a lipase activator and of a fat-emulsifying agent a vegetablelipase-yielding material in an aqueous medium.

21. A process of making a tanning preparatory liquid which consists in fermenting a mixture comprising water, disintegrated castor oil seed, a lipase activator and an alkali sulphoricinate.

22. A process of making a tanning preparatory liquor which consists in fermenting in presence of a lipase activator a lipaseyielding material in an aqueous medium in the presence of developing lactic yeast.

23. A process of making a tanning preparatory liquor which consists in fermenting in presence of a lipase activator a mixture comprising water, disintegrated castor oil seed, and developing lactic yeast.

' mg in presence of manganese sulphate a mixture comprising water, disintegrated castor oil seed, and developing lactic yeast at a temperature substantially between 26 and 28 C.

26. A process of making a tanning preparatory liquor'which consists in fermentin a mixture comprising water, disintegracastor oil seed, an alkali sulphoricinate, and

sulphate ofmanganese in substantially the proportions. of 200 lbs. of water, 55 lbs. of castor oil seed pulp, 2 lbs. of the alkali sulphoricinate, and one-fifth to 1 oz. of the manganese salt.

27. A process of making a tanning preparatory liquor which consists in growing lactic yeast in a culture mediumcontaining disintegrated castor oil seed, and then adding the so-activated yeast culture to a mixture comprising water and disintegratedcastor oil seed, and fermenting said mixture comprising the, yeast culture in. presence of manganese sulphate. V I

28. A process of making a tanning prepar atory liquor which consists in growing. lactic east in a culture medium initially containmg a small proportionof an alkali sulphoricinate, and gradually increasing the proportion of sulphoricinate during the growth of the yeast in the medium, and then adding the so-activated yeast culture to a mixture comprising water and disintegrated castor oil seed and fermenting said mixture containing the yeast culture in presence of a manganese salt.

In testimony whereof I aflix my signature.

CHARLES JOSEPH MICHEL MARIE LE PETH'. 

